SMS is a communication protocol allowing the interchange of short text messages (e.g., 160 characters) between mobile devices. MMS is an extension of SMS allowing the interchange of messages of any length, which may also include multimedia content. Messaging has become such a popular mode of communication that certain mobile users use messaging more frequently than voice calls. Herein use of the term SMS will refer to 1) SMS; 2) MMS; and 3) collectively both SMS and MMS as necessary to delivery desired content between mobile devices.
SMS messages are presently transmitted over signaling channels of a voice network, such as over SS7 channels. A typical voice network includes a Radio Access Network (RAN) and a core network. The RAN provides an air interface to a mobile device. The core network connects the RAN to other networks, such as the Public Switched Telephone Network (PSTN) or another RAN. The core network includes a switching system and a subscriber database for serving the mobile device.
For instance, in a Universal Mobile Telecommunications System (UMTS) network, the switching system may comprise a Mobile Switching Center (MSC) and the subscriber database may comprise a Home Location Register (HLR). In an IP Multimedia Subsystem (IMS) network, the switching system may comprise a Call Session Control Function (CSCF) and the subscriber database may comprise a Home Subscriber database (HSS).
The core network also connects to a SMS Center (SMS-C). The SMS-C is the entity which performs the storing and forwarding SMS messages to and from mobile devices. As an example of delivery of a Mobile Terminated (MT) SMS message to a mobile device, in a UMTS network, the SMS-C receives an SMS message destined for the mobile device, and stores the SMS message. The SMS-C then queries the subscriber database (i.e., HLR or HSS) for routing information based on the location of the mobile device. Then, the SMS-C attempts to deliver the SMS message to the destination by routing the SMS message to the appropriate MSC through an SS7 channel. The MSC receives the SMS message from the SMS-C, and forwards the SMS message through the RAN to the mobile device using a signaling channel.
For delivery of a Mobile Originated (MO) SMS message, a sending party enters the content and intended destination (e.g., a phone number or an address) of the message into a mobile device, which sends the SMS message to the MSC over the RAN, again using a signaling channel. The MSC that is serving the mobile device receives the SMS message, and routes the SMS message to the SMS-C. The SMS-C stores the SMS message, and attempts to forward the SMS message to the destination, again querying the subscriber database (i.e., HLR or HSS) for routing information associated with the destination.
3rd Generation Partnership Project (3GPP) has finalized the Release 8 specifications of the Long Term Evolution (LTE) and the Evolved Packet Core (EPC) network architecture. The EPC is a multi-access core network based on the Internet Protocol (IP) that enables operators to deploy and operate one common packet core network for 3GPP radio access (e.g., LTE, 3G and 2G), non 3GPP radio access (e.g., High Rate Packet Data (HRPD), Wireless Local Area Network (WLAN), and Worldwide Interoperability for Microwave Access (WiMAX)), and fixed access (e.g., Ethernet, Digital Subscriber Line (DSL), cable, and fiber).
3GPP specifications rely on legacy SMS-C (including MMS-C) for messaging delivery attempt in the LTE/EPC network (i.e., the store and forward mechanism for message delivery described above) even when there are multiple radio access and non radio access available. Accordingly, conventional SMS over LTE will require a SMS-C or Internet-Protocol Short-Message Gateway (IP-SM-GW) to query the HSS or Authentication, Authorization and Accounting (AAA) Server on subscriber access status every time when delivering a SMS message.